Update Image Compatibility Table in README.md to Include Latest Operator Versions

Description of the issue The Image Compatibility section in the README currently only lists information up to operator version v0.19.x. However, newer releases are available (e.g., v0.21.0), and it’s not clear which Redis, Sentinel, and Exporter image versions are compatible with these newer operator versions.

As a user, I’m unable to determine which versions should be listed as compatible. The maintainers or contributors who know the tested/verified image versions would need to provide this information.

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What I expected The compatibility table should list entries for all operator versions up to the latest release, including v0.21.0, with the corresponding supported versions of:

• Redis image
• Sentinel image
• Exporter image

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Why this matters

• Users rely on this table to pick safe and tested image versions.
• Without updated compatibility info, it’s unclear which versions are officially supported with the latest operator.
• This creates uncertainty when deploying new versions.

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Steps to reproduce the problem

1. Visit the Image Compatibility section in the README.
2. See that the table stops at v0.19.x.
3. Compare this with the latest releases, where newer versions exist (e.g., v0.21.0).

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Suggested resolution

• Add compatibility entries for the latest operator versions (v0.20.x, v0.21.x, etc.).
• If possible, note whether the latest tag aligns with a specific tested image set.

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Additional context I don’t know what needs to be checked to define compatibility, so unfortunately I cannot open a PR with exact versions. I’m opening this issue to flag the missing information so the maintainers can provide the authoritative details.